1. Field of the Invention
This invention relates to computer memory technology, and more particularly, to an access control unit and method for use with an SDRAM (Synchronous Dynamic Random Access Memory) chip for controlling a burst transfer access operation on the SDRAM chip.
2. Description of Related Art
SDRAM (Synchronous Dynamic Random Access Memory) is an advanced type of DRAM (Dynamic Random Access Memory), which is characterized by that the data access rate is synchronized with CPU's clock signal, allowing the CPU to retrieve data from SDRAM without latency so that the access speed is increased. An SDRAM device operates in two modes: interleaved mode or sequential mode.
With the above-mentioned SDRAM characteristics, the required access control circuitry for an SDRAM chip should be designed to comply with these requirements so as to be able to perform the data access operations.
One drawback to conventional SDRAM access control units, however, is that the burst length in each burst transfer access operation is a fixed amount of data, such as 8 bits or 16 bits, and cannot be changed arbitrarily.
Still another drawback of conventional SDRAM access control units is that at the completion of each burst transfer access operation, a burst stop command or a precharge interrupt method should be used to terminate the burst transfer access operation, which makes the required logic circuitry more complex in structure.